Sustainable, antifouling poly (ethylene furanoate)/ poly (lactic acid) (PEF/PLA) blend electrospun nanofibrous membranes for switchable premix emulsification/demulsification

Sustainable polymer materials are emerging as promising alternatives in the filtration sector due to the adverse environmental impacts and persistence of synthetic polymers. This study reports the fabrication of sustainable blend electrospun nanofibrous membranes (ENMs) for switchable membrane emulsification/demulsification of oil-in-water (O/W) premix emulsion and water filtration. The optimized 2:3 PFLA (2PEF: 3PLA) electrospun nanofibrous membrane (ENM) exhibited superior chemical, mechanical, thermal, and permeation properties compared to membranes made from pure PEF and PLA. The tunable hydrophilicity of the optimized ENM was attributed to trifluoroacetic acid (TFA)-induced solvation/scission effects on the polymer chains, resulting in superhydrophilicity, as demonstrated by a dynamic contact angle of 0° after 5 s. Moreover, it exhibited excellent hydrophilic efficacy, with significantly high water flux (9.99 × 10⁴–60.19 × 10⁴ L m⁻² h⁻¹) at various pressures (1–5 bar), along with strong fouling tolerance, high rejection, and a substantial flux recovery ratio. A switchable emulsification/demulsification phenomenon was observed during the extrusion of premix emulsions through the 2:3 PFLA ENM, governed by the transmembrane pressure and surfactant-to-oil ratio (C_S/C_O). During emulsification, the droplet size of the premix decreased from 67 μm to 5.4 μm, while during demulsification, it increased from 37 μm to 230 μm. This study advances the applications of PEF and opens a new direction for sustainable membranes towards switchable premix membrane emulsification/demulsification as well as fouling-tolerant water filtration applications.